Hydraulic power steering mechanism for vehicle having articulated sections



B. J. M COLL 2,967,582 HYDRAULIC POWER STEERING MECHANISM FOR VEHICLE HAVING ARTICULATED SECTIONS Original Filed Oct. 15, 1956 Jan. 10, 1961 4 Sheets-Sheet 1 FIG. l

INVENTOR.

BRUCE J. MCCO LL MHz/I3:

AT TY.

Jan. 10, 1961 B. J. M COLL HYDRAULIC POWER STEERING MECHANISM F OR VEHICLE HAVING ARTICULATED SECTIONS Original Filed Oct. 15, 1956 4 sheets-sheet 2 INVENTOR.

BRUCE J. M COLL ATTY.

mm on m a mw on Jan. 10, 1961 B. J. M COLL HYDRAULIC POWER STEERING MECHANISM FOR VEHICLE HAVING ARTICULATED SECTIONS Original Filed Oct. 15, 1956 4 Sheets-Sheet 5 E a F w 2 mm 4:

Mm LWH MW HIM! YI m9 0: m9 #9 mm m g 8. mm mm 0 mm INVENTOR.

BRUCE J. MCCOLL Maw/i ATTY.

B. J. McCOLL 2,967,582 HYDRAULIC POWER STEERING MECHANISM FOR I HAVING ARTICULATED SECTIONS 1 4 SheetsSheet 4 Jan. 10, 1961 Original Filed Oct.

INVENTOR.

BRUCE J. M COLL ATTY.

Wax/j Patented Jan. 10, 1961 Free HYDRAULIC POWER STEERING MECHANISM FDR VEHICLE HAVING ARTICULATED SEC- TIONS Bruce J. McCall, Strathmore, Quebec, Canada, assignor to Clark Equipment Company, a corporation of Michigan ()riginal application Oct. 15, 1956, Ser. No. 615,869,

new Patent No. 2,884,083, dated Apr. 28, 1959. Divided and this application Aug. 13, 1958, Ser. No. 754,816

Claims priority, application Canada Oct. 21, 1955 Claims. (Cl. 180-79.2)

Thi invention relates to vehicle steering mechanisms and more particularly to power steering mechanisms in which a servomotor is utilized to turn one part of the vehicle with respect to another in order to accomplish steering.

This application is a division of my co-pending application, Serial No. 615,869, filed October 15, 1956, now Patent No. 2,884,083 dated April 28, 1959.

The principal object of the present invention is to provide a simple, rugged and low cost steering mechanism which may be used with off-the-road and other heavy duty vehicles which are subjected to very hard service. The invention is described and illustrated herein as applied to an articulated vehicle intended for use in logging operations and the like. However, it will be appreciated by those familiar with mechanisms of this type that my steering mechanism is not limited to use with such vehicles but may be used also with other more common types of vehicles.

A more specific object of my invention is to provide a power steering mechanism of simple and rugged construction in which the servomotor is located remotely from the turning or steering axis.

A still further object is the provision of such a power steering mechanism in which a reciprocating servomotor or actuator having a long stroke may be employed, without interfering with the operation of any other parts of the vehicle.

A feature of my invention is that the reciprocating servomotor employed therein may be located in such a position on the vehicle that it is better protected and less susceptible to shocks and abuse than is the case with most known power steering mechanisms of which I am aware.

In carrying out my invention in one form I provide a steering mechanism for an articulated vehicle having two chassis parts joined by a coupling which provides for the pivotal movement of one chassis part with respect to the other about a vertically disposed axis to accomplish steering. The steering mechanism includes a laterally extending steering arm rigidly mounted on one chassis part and a supporting link pivotally mounted on the other chassis part and extending laterally in the opposite direction. A connecting link joins the steering arm and the supporting link, being pivotally connected to both, forming a Z-shaped structure. A double acting, cylinder and piston type, fluid servomotor is mounted on the second chassis part and pivotally connected to the connecting link. Extension and retraction of the servomotor moves one chassis part with respect to the other and steers the vehicle in the desired direction.

For a clearer and more complete understanding of my invention reference should be had to the accompanying drawing in which:

Figure 1 is a plan view of a vehicle embodying the steering mechanism of this invention. The superstructure of the vehicle has been omitted for clarity of illustration,

Figure 2 is a side elevational view corresponding to Figure 1.

Figure 3 is a detailed sectional side elevational view of the coupling portion of the vehicle.

Figure 4 is a diagrammatic plan view of a portion of the vehicle showing the positions of various parts thereof when the vehicle is being turned.

Figure 5 is a diagrammatic end elevation view of the coupling and rear chassis of the vehicle illustrating oscillatory movement provided between the coupling and the rear chassis.

Referring now to Figures 1 and 2 of the drawing, the vehicle illustrated comprises a front chassis designated generally by the numeral 10, and a rear chassis designated generally by the numeral 11. The front chassis 10 and the rear chassis 11 are connected together by a coupling designated generally at 12.

The front chassis 10 of the vehicle includes a framework having longitudinal members 13 and transverse members 14 and 15. A platform 16 to support the engine is mounted on transverse members 14 and 15. The frame of the front chassis also includes trunnion supporting members 17 and 18 which are angularly disposed to each other in the form of a rearwardly directed V. A platform 19 is mounted on trunnion supporting frame members 17 and 18. Wheels 20 support the front chassis and are mounted on axial shafts 21, which are directly journalled by bearings 22 on longitudinal frame members 13. It will be particularly noted that no conventional spring suspensions are needed. The rear chassis 11 comprises longitudinal frame members 23 con nected together at their front ends by transverse frame member 24. The rear chassis 11 is supported by wheels 25 mounted on axle shafts 26 which are directly mounted by bearings 27 at the ends of longitudinal frame members 23.

Engine 28 drives input shaft 29 of transmission 30. As illustrated in Figure 1, universal couplings 31 and 32 respectively conveniently provide for coupling the output of engine 28 with shaft 29 and for coupling shaft 29 with the input to transmission 30. Engine 28 is also provided with a power take off 33 for the pump 34 which generates hydraulic pressure to steer the vehicle. Engine 28 also has a power take off 35 which drives generator 36 through universally coupled shaft 37.

Transmission 30 is a conventional transmission having,

however, power outputs for both front and rear wheel drives. Front wheel drive shaft 38 is linked by universal coupling 39 to transmission shaft 40, to drive transmission 41 which in turn drives front axle shafts 21. The transmission shaft 48 also drives rear wheel drive shaft 42 which is coupled to transmission shaft 40 by universal coupling 43. Rear wheel drive shaft 42 is linked by universal coupling 44 to a drive shaft 45 (see Figure 3 for details) which is journalled in bearing 46 and to which is connected brake drum 47. A telescopically extensible shaft 48 is driven by shaft 45 through universal coupling 49, and is joined by universal coupling 50 to drive shaft 51. Drive shaft 51 is, as will subsequent ly be apparent from Figure 3, journalled within horizontal trunnion 52. Shaft 51 is connected by universal coupling 53 to tail shaft 54 which drives the input 55 to rear wheel transmission 56 through universal coupling 57. Rear wheel transmission 56 drives axle shafts 26.

The coupling 12 includes a web 58 to which a steering arm 59 is connected by bolts 60. A link 61 is pivotally connected by pin 62 to the free end of steering arm 59. The other end of link 61 is pivotally connected by a pin 63 to a supporting link 64 which in turn is pivotally mounted by pin 65 on flange 66, which is connected to longitudinal frame member 13 to form part of the front chassis. The piston rod 67 of a piston and cylinder type double acting hydraulic actuator 68 is pivotally connected by pin 69 to the center of link 61. Pin 62 is substantially the same distance from vertical trunnion 70 which provides the point of articulation between the front and rear chassis, as the length of link 64'.

Accordingly, due to the central connection of pin 69 with link 61, hydraulic actuator 68 steers the vehicle without any substantial lateral displacement of hydraulic actuator 68. Hydraulic actuator 68 is mounted on a longitudinal frame member 13 by mounting bracket 71 which is connected to hydraulic actuator 68 by pivot pin 72 to provide for any slight lateral movement which might be necessary during steering. The elimination of substantial lateral movement of hydraulic actuator 68 makes it possible to use a long stroke hydraulic actuator without it being necessary to provide excessive space to accommodate lateral swinging of the hydraulic actuator. Suitable hydraulic connections (not shown) are provided to actuate hydraulic actuator 68 from pump 34.

Referring now to Figure 3 of the drawing, vertical trunnion 70 comprises a cylindrical tube 73 which has a plug 74 at its upper end and which is connected to the front chassis by means of a sleeve 75, secured to tube 73 by bolt 76. Sleeve 75 is rigidly secured to frame member 19.

Horizontal trunnion 52 is secured to the rear chassis 11 by bolt 77 which fastens the cylindrical tube 78 which provides rear trunnion 52 to a sleeve 79 which is rigidly secured as part of transverse frame member 24. Web 58 is provided with a pair of spaced bearing members 80 and 81 which engage the portions of cylinder 73 which are respectively above and below sleeve 75. Web 53 is also provided with a pair of spaced bearing portions or members 82 and 83 to receive the portions of trunnion cylinder 78 which extend respectively to the rear end of and forwardly with respect to sleeve 79. Preferably web 58 and bearing members 80, 81, 82 and 83 are formed as an integral casting. Bolt holes 84 are provided in web 58 for the attachment of steering arm 59.

Bearing 46 for shaft 45 is supported by mounting plate 85 which is secured to frame members 17 and 18. Bearing 46 comprises a bearing sleeve 86 to which is secured an annular flange 87. This flange 87 is connected by bolts 83 to plate 85. Roller bearings 89 and 90 disposed within sleeve 86 support shaft 45. Yoke 91 is splined at 92 to the forward end of shaft 45 to form part of universal coupling 44. Brake drum 47 is also secured to yoke 91 by bolts 93. At the rear end of shaft 45 is splined yoke 94 which forms part of universal coupling 49. Telescopically extensible shaft 43 is provided by a shaft 95 having splines 96 which are slidably engageable with the splines 97 of an internally splined sleeve shaft 98. Sleeve shaft 98 is linked by bolts 99 to universal coupling 49 and has a threaded cap 10% retaining gasket 101. Shaft. 95 is connected by bolts 102 to universal coupling 50. which includes a yoke portion 103 splined at 104 to shaft 51. Shaft 51 is journalled within the trunnion provided by cylinder 78 by bearings 105 and 106. Suitable seals 107 and stoneguards 108 provide for bearings 105 and 106. Shaft 51 is splined at 109 to portion 110 of universal coupling 53.

Bearing sleeves 111 and 112 are provided for bearing members 80. and 81 and similarly bearing sleeves 113 and 114 are provided for bearing members 82 and S3. Gaskets 115 and 116 are provided between bearing member 80 and sleeve 75 and between sleeve 75 and bearing member 81 respectively. Similarly, gaskets 117 and 118 are provided between sleeve 79 and bearing members 82 and 83 respectively. 3

It will be noted that the coupling construction which hasbeen described provides relative movement about the vertical axis between-.webSS and frame member 19 of the front chassis, thereby enabling the vehicle to be steered and also gives oscillatory movements about a horizontal axis due to relative, rotation which: can occur between sleeve 79 which is mounted on the rear chassis and web 58. In addition, the drive from the engine to the rear wheels is conducted through trunnion 52 with the assistance of universal couplings 49 and 50, and the telescopically extensible shaft 48 which lies between universal couplings 49 and 50.

Figure 4 shows the relative positions of front chassis 10 and rear chassis 11 when the vehicle is being steered towards the left. Figure 4 shows the extreme position with trunnion steering stop projections 119 abutting against portion 120 of web 58. In Figure 4, the maximum relative movement provided between the front and rear chassis, front stop to stop, is degrees, including 45 degrees either side of the straight ahead position. It will be apparent from Figure 4 that an exceedingly small turning circle is provided for.

Figure 5 shows the limit of relative oscillatory movement between the web 58, trunnion 52, and the transverse frame member 24 of the rear chassis. Abutment is provided between portion 121 of transverse frame member 24 and stop face portion 122 of web 58. The maximum movement provided for in the embodiment as illustrated in Figure 5 is 40 degrees, consisting of 20 degrees of movement on either side of the vehicle position on a horizontal surface.

It will be noted that the extent of relative vertical movement thus provided between wheels 25a and 25b is far greater than would be achieved using conventional spring suspensions, and at the same time the complexities and weaknesses of conventional spring suspensions are avoided.

I claim:

1. In an articulated vehicle having a front chassis and a rear chassis, a coupling for connecting said front chassis to said rear chassis comprising a vertical trunnion, means for mounting said vertical trunnion on one of said chassis, a horizontal trunnion, means for mounting said horizontal trunnion on the other of said chassis, and a coupling web, bearing means on said coupling web to receive said vertical trunnion, additional bearing means on said coupling web to receive said horizontal trunnion, the bearing means on said coupling web receiving said vertical trunnion being adapted to permit limited movement between said front chassis and said rear chassis about a vertical axis, the additional bearing means on the coupling web receiving the horizontal trunnion being adapted to permit relative oscillation between said front chassis and said rear chassis about a horizontal axis, a steering arm connected to said coupling web and extending laterally therefrom, a double acting cylinder and piston hydraulic mechanism mounted on the said front chassis, a link eonnecting the piston rodv of said hydraulic mechanism to the end of said arm, said piston rod being connected to substantially the centralportion of said link, and a supporting link for said link connected between said front chassis and the end of said link which is remote from the steering arm, the steering arm extending from said link in one direction and said supporting link extending from said link in a direction opposite to said one direction and the length of said supporting link being substantially the same as: the length of the. steering arm to enable said double acting hydraulic mechanism to control the position of said steering arm without substantial lateral displacement of said hydraulic mechanism.

2. In an articulated vehicle having a front chassis and a rear chassis, a combined draft and steering coupling connecting said front chassis to said rear chassis including means permitting movement of said rear chassis with respect to said front-axis about a vertically disposed axis, a steering arm connected to a portion of the said coupling and extending laterally therefrom, an elongated double actingservomotor having one end thereof mounted on one of the said chassis, a link connecting the opposite end of said servomotor to the end of the said arm, said opposite end being connected substantially centrally of,

said link, and a supporting link for said link connected between said one chassis and the end of said link which is remote from the steering arm, the steering arm extending from said link in one direction and said supporting link extending from the link in the opposite direction and the length of the said supporting link being substantially the same as the length of the said steering arm to enable said double acting servomotor to control the position of said steering arm without substantial lateral displacement of said servomotor.

3. A steering mechanism for a vehicle having a first part pivotally movable with respect to a second part to accomplish steering of the vehicle, comprising a steering arm adapted to be rigidly mounted on one part of the vehicle and extend laterally therefrom, a supporting link adapted to be pivotally mounted on the other part of the vehicle and extend laterally from the pivot in substantially the opposite direction to said steering arm, a connecting link pivotally connected to the said steering arm remotely from its said rigid mounting and to the said supporting link remotely from its said pivotal mounting, and a servomotor pivotally connected to the said connecting link intermediate its connections to the said steering arm and the said supporting link and adapted to be mounted on the other part of the vehicle.

4. In a steering mechanism for a vehicle having one part pivotally movable with respect to another part to accomplish steering of the vehicle, a horizontally disposed linkage comprising three elongated members arranged in approximately Z-shaped configuration in the straight-ahead position of the vehicle and arranged with the connecting member of the Z pivotally joined at its ends to opposite ends of the other two members and with the said other two members transversely disposed, one of said transversely disposed members being rigidly mounted at its other end on one part of the vehicle, the other transversely disposed member having its other end pivotally mounted on the other part of the vehicle, and a servo motor mounted on the other part of the vehicle and pivotally connected to the said connecting member intermediate the ends thereof.

5. A steering mechanism for an articulated vehicle having a chassis comprising two parts connected by a coupling which permits pivotal movement of one chassis part with respect to the other about a vertically disposed axis to accomplish steering of the vehicle, the steering mechanism comprising a steering arm rigidly mounted on one chassis part and extending laterally therefrom, a supporting link having one end pivotally mounted on the other chassis part and extending laterally therefrom in substantially opposite direction to said steering arm, a connecting link pivotally connected to the other end of the said supporting link and to the free end of the said steering arm, and a reciprocating servomotor pivotally mounted on the other chassis part and pivotally connected to the said connecting link intermediate its connection to the said steering arm and the said supporting link for steering the vehicle in the selected direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,638,998 Rochwell May 19, 1953 

